The research I propose to undertake has two goals: 1) to establish in culture nerve cell lines from discrete regions of the brain, specifically the cerebellum; and 2) to characterize these lines with respect to their neuronal properties (excitability, neurotransmitter synthesis, etc.), paying special attention to adult characteristics. I intend to establish the lines by incorporating into nerve cells via direct viral integration or chromosomal transfer, the transforming gene of temperature-sensitive Rous sarcoma viruses (TS-RSV). Recently, it has been shown that the transforming gene of TS-RSVs can reversibly control the expression of differentiated functions of the host cell. At the permissive temperature the product of the transforming gene is active and suppresses the expression of differentiated properties, while--and this is the key observation--at the nonpermissive temperature the transforming gene product is inactivated and the cell resumes its normal state both morphologically and biochemically. Therefore, I propose to infect normal differentiated nerve cells at the permissive temperature and produce cloned cell lines. Then, at the nonpermissive temperature, remove the transforming gene effect with the result that cells will begin to express those highly differentiated characteristics associated with a terminally differentiated neuron. The identification and characterization of the lines will be based on known biochemical and morphological markers characteristic of a specific cerebellar neuron. Studies will be aimed at determining the enzymatic and neurotransmitter content of the lines as well as their capacity to form synapses.